Hi! What I did when this happened was to uninstall Starcraft and Battle.net app, restart the PC, then delete all the remaining Blizzard and Starcraft folders (if any). Be careful to not delete the folders for other Blizzard games, if you got more of them installed.
I used Everything by voidtools to aid me in finding and removing the remaining folders:
https://www.voidtools.com/
Once Everything starts, let it index all the files, then go to View > Filters. Now select “Folders” from the dropdown menu and look for the respective folders.